In the construction of reinforced masonry walls and/or concrete slabs, it has been conventional practice in the past to erect spaced temporary forms, between or upon which standard reinforcing members are placed, following which approximatey 150 pcf. density of high structural strength concrete is poured between or upon the forms, and vibrated.
After the forms are erected, or as they are in the process of being erected, portions thereof are cut out for mechanical or electrical egress and door and window frames are attached for openings by means of built-in bucks. Cutting these forms results in costly repair if the forms are to be reused.
After the concrete cures, the forms are removed, requiring a time element which is costly, and finishes are usually applied to one or both outer faces of the resulting section. If the exposed face is to be used as a flat finish, the surfaces must be pointed up where snap ties are broken off, which hole areas are noticeable without a supplementary finish, and act as a capillary conduit for moisture through the wall.
If the walls are to be considered waterproof, an additional treatment must be applied to the face exposed to the elements. If the walls are a part of a residence, architectural concrete finishes must be applied or provided by form liners, resulting in additional expense in time and material, and damage thereto.
Since conventional concrete walls or slabs do not provide sufficient insulation value to meet today's standards for energy conservation, additional applications of insulation must be applied requiring an additional application to the interior face for a finished wall surface, involving even greater time and expense. In the case of roof slabs, additional insulation and wearing surface must be added. Any use of conventional concrete automatically dictates 30% additional weight (as compared to the same section in structural grade cellular concrete) is added to the dead load imposed upon the reinforcing, structural framework and/or foundations.
In the construction of conventional masonry walls, the physical time and cost factors are even less favorable than set out above. Finishes are usually restricted to exposed brick or hollow block, or applied finishes such as stucco or additional precast finishes. The thickness of the load-bearing walls must be greater than concrete and reinforced concrete beam and column sections must be provided within the masonry section resulting for it to be considered load-bearing. This involves extra trades in addition to the wet trades, which slow down a job to a considerable degree and also increase its costs both in material and labor.
Besides a marked inferiority in load bearing capability as compared to reinforced concrete, conventional masonry construction has little or no resistance or lateral stress. Hollow block masonry is particularly susceptible to moisture invasion, as well as vermin, and has little value in fire rating or as an insulating factor against sound or thermal conduction. In consideration of these defects, conventional masonry must be reinforced, and additional applications be made to its surfaces, both inside and outside, to overcome its weaknesses and gain some portion of the aesthetic and physical properties noted above.